You wash the cars, mow the lawn, perhaps spend a little recreation time at the pool with the kids. If the kids are in luck, you might even spend a few minutes launching them through the air into the water. Monday morning arrives, you drag yourself out of bed and head to work. You bend over to pick up a wrench or that slip of paper on the floor, and instantly your back goes out. It feels like someone has thrust a hot dagger into your back. You wince, stagger to a chair and realize you have just ruined the next week. This is an all too real scenario. In fact, work-related injuries occur more commonly on Monday than on any other day. But this need not be the case. Heightened physical activities, such as occur over the weekend, often push muscles to their limit, causing a buildup of lactic acid which leads to muscular soreness and tightness. It is this exact stiffness that renders the muscles more susceptible to sprains and strains. On a microscopic level, a sprain or strain occurs when the muscle fibers literally tear themselves apart. Obviously, the greater force applied, the greater the resultant injury. This can be largely avoided by one simple bit of advice: stretch your hamstrings. As a muscle group, the muscles in the back of the thighs, the hamstrings, constitute the most powerful muscles in the body and they easily dwarf the lumbar muscles in power. As you bend over, it becomes a tug of war between the hams and the lumbar muscles, and the lumbar muscles usually lose out, resulting in a muscle injury. My simple advice: spend a few minutes every morning, and particularly on Mondays, stretching your hamstrings. There are several ways to do this. Lie on your back and pull your knee up to your chest. Alternatively, put your foot on a chair or low bench and lean your torso forward. You feel the stretch. Do it every day and you will see a remarkable difference.